Heated Oxygen Sensor (HO2S) Inspection

HEATED OXYGEN SENSOR (HO2S) INSPECTION

NOTE: Perform the following inspection only when directed.

Voltage Inspection

1. Warm-up the engine and run it at idle.
2. Disconnect the HO2S connector.




3. Connect the voltmeter test leads to the following HO2S terminals:
- (+) lead-terminal A
- (-) lead-terminal B

4. Run the engine at 3,000 rpm until the voltmeter moves between approx. 0 and 1.0 V.




5. Verify that the measurement voltage changes when the engine speed increases and decreases suddenly several times.
- If the HO2S is okay, but the PID value is out of specification, perform the "Circuit Open/Short Inspection".
- If not as specified, replace the HO2S. (See EXHAUST SYSTEM REMOVAL/INSTALLATION.)

Circuit Open/Short Inspection

1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION.)




2. Inspect the following harness for open or short circuit. (Continuity check)

Open circuit
- HO2S (RF) terminal A (harness-side) and PCM terminal 60 (harness-side)
- HO2S (RF) terminal B (harness-side) and PCM terminal 91 (harness-side)
- HO2S (LF) terminal A (harness-side) and PCM terminal 87 (harness-side)
- HO2S (LF) terminal B (harness-side) and PCM terminal 91 (harness-side)
- HO2S (RR) terminal A (harness-side) and PCM terminal 35 (harness-side)
- HO2S (RR) terminal B (harness-side) and PCM terminal 91 (harness-side)
- HO2S (LR) terminal A (harness-side) and PCM terminal 61 (harness-side)
- HO2S (LR) terminal B (harness-side) and PCM terminal 91 (harness-side)

Short circuit
- HO2S (RF) terminal A (harness-side) and power supply.
- HO2S (RF) terminal A (harness-side) and body GND.
- HO2S (RF) terminal B (harness-side) and power supply.
- HO2S (LF) terminal A (harness-side) and power supply.
- HO2S (LF) terminal A (harness-side) and body GND.
- HO2S (LF) terminal B (harness-side) and power supply.
- HO2S (RR) terminal A (harness-side) and power supply.
- HO2S (RR) terminal A (harness-side) and body GND.
- HO2S (RR) terminal B (harness-side) and power supply.
- HO2S (LR) terminal A (harness-side) and power supply.
- HO2S (LR) terminal A (harness-side) and body GND.
- HO2S (LR) terminal B (harness-side) and power supply.